Metal transfer device



Dec. 11, 1934. J, A. NocK, JR

METAL TRANSFER DEVICE Filed Dec. 3, 1952 INVENTOR JZPJE/O/ /Vo CK, Je,

ATTORNEY Patented Dec. 11, 1934 UNITED STATES PATENT OFFICE AluminumCompany of America, Pittsburgh,

Pa., a corporation of Pennsylvania Application December 3, 1932, SerialNo. 645,510

4 Claims.

This invention relates to the transfer of molten metal. It relates inparticular to the provision of an improved device for use in combinationwith a transfer apparatus of the vertical discharge type, such as asiphon, for example, to secure simultaneously the quiet transfer ofmolten metal and the removal of dross therefrom.

In pouring most castings, but especially in casting ingots to be rolledinto sheet, diiculty is encountered in preventing the inclusion of somedross or oxide material, which usually oats on the surface of the metalin the casting crucible. This is particularly true with the lightmetals, such as aluminum for example, due to the rela- Atively highspecific gravity of the dross materials and the relatively low specificgravity of the metal. In the vertical type of transfer apparatus,further dimculty is encountered due to the high velocity of thedischarge which, if unchecked, often creates a turbulence violent enoughto entrap dross and cause it to become intimately entrained in the metalcast, which at times leads to serious defects.

The primary object of my invention is to provide a device for use incombination with a metal transfer device having a vertical dischargewhich will remove the dross and greatly retard the velocity of thestream of metal discharged.

A further object is to provide a device which will overcome thedifficulties described hereinabove and which is simple and convenient tooperate and of strong and rugged design.

This and other objects and attainments will be more fully appreciatedupon reference to the following description and the accompanyingdrawing, in which:

Fig. 1 is a vertical sectional view of a preferred embodiment of myinvention, taken on the center line I-I of Fig. 2, with parts inelevation; A

Fig. 2 is a perspective view of my improved device; and

Fig. 3 is a diagrammatic view showing partially in vertical section andpartially in elevation an assembly for the transfer of molten metal inoperating position between and connecting a receiver partially lled withmolten metal and a crucible containing molten metal.

Referring to the drawing, in which like reference numerals have beenused to designate like parts, Figs. 1 and 2 show the end of a verticaldischarge tube 1 of a Siphon or other metal transfer device providedwith a device 2 for diffusing metal and removing dross therefrom inaccordance with my invention. The end of the tube' is closed by securelyfastening it to the bottom of the tray or similar device 2, as bywelding or other suitable means. Lateral ports 3 are cut in the tube,adjacent but usually somewhat above its lower end, and preferably onopposite sides of the tube and along the longitudinal axis of the tray,as shown. Other symmetrical arrangements of the ports may sometimesbe-used, however. Transverse slots 5 are formed in the bottom of thetray, and extend substantially across the bottom thereof. The combinedarea of these slots is preferably several times the combined area of theports 3 in the tube l. These transverse slots constitute an importantfeature of my invention. I have found that a screening and diffusingdevice of the type described but having a. bottom perforated with roundholes or openings of other shape having a maximum dimension smaller thanthat of the preferred slots is operative, but I have found that becauseof the increased Wall surface exposed to the metal, the consequentlyincreased friction, and/or the increased tendency for such holes toclose, and sometimes for other reasons, a device having a bottom soconstructed is not as satisfactory or eicient as a device having bottomopenings in the form of slots of substantially the same combined area. Ihave also found that it is preferable to arrange the slots transverselyin relation to the current set up on the tray by the flow from theopenings 3, rather than parallel with it. The sides 6 of the tray arecustomarily formed integral vwith the bottom plate, and are high enoughto extend above the ports 3 in the discharge tube 1. The tray ispreferably of rectangular shape, but may be square or round or ofsubstantially any shape required to best adapt it to the conditions ofpouring. It is essential, however, to allow suficient distance betweeneach port 3 and the side Wall of the tray so that the force of thestream discharged through the ports will be diffused by the body ofmolten metal in the tray before the metal passes through the slots inthe bottom of the tray into the receiver.

While my invention is generally adapted for use in casting operationsemploying a transfer apparatus of the type described, I have chosen todescribe in detail its application to the casting of aluminum ingots, asthis example of its application illustrates fully the advantages of myinvention and constitutes a preferred embodiment thereof.

The assembly shown in Fig. 3 consists of a siphon '1, a crucible 8, andan ingot mold 9. The crucible contains molten aluminum 10 which is beingtransferred through the siphon into the mold. The mold is preferablysupported on a hydraulic piston (not shown or analogous known deviceadapted to lower it as the metal level rises. The vertical discharge end1 of the siphon 7 is firmly connected to a screening and diiTusingdevice 2, as described hereinabove, and the mold 9 is lowered relativelyto the crucible 8 during the pouring operation so that the metal levelin the tray 2 is kept below the top of the side walls 6 thereof butabove the ports 3 in the pipe 1. Associated with the crucible or thesiphon is a suitable device for starting the flow of metal through thesiphon. This may take the form of a displacement device 11, such as aweight or a hollow weighted vessel, which is supported by a chain 12 orthe like from a crane (not shown) or other adjustable supporting means.Other known means for starting the flow of metal through the siphon maybe substituted for the displacement device, and it is to be understoodthat other types of transfer apparatus terminating in vertical dischargetubes 1, such as pouring spouts, may be substituted for the siphonshown. When a siphon is used, it is preferably placed in a notch or slot13 in the side of the crucible 8. If desired, the Siphon or othertransfer device and/or the screening and diffusing device may be given alime-wash or other protective coating in known manner to protect it fromattack by the metal being transferred. It is then preferably heated atleast sufficiently to free the surface from moisture.

'I'he siphon 7 is lowered by a hoist or other suitable means into thestarting position, with its intake end near or on the bottom of thecrucible 8 and its discharge end with the tray 2 amxed thereto restingon the bottom of the mold 9. The molten metal 10 rises in the intake legof the siphon to a level substantially equal to the level 4m of themetal in the crucible, which is preferably nearly but not quite highenough to start the siphon. The displacement member 11 is then loweredrapidly into the metal, raising its level sufficiently to start the flowof metal through the Siphon, or the siphon may be started in some othermanner.

The initial flow of metal quicklylls the tray due to the resistance ofthe small opening between the tray and the bottom of the mold to theflow of metalvtherethrough, and inra relatively brief period of time thelevel of the metal in the tray and in the mold rises over the level ofthe ports 3 in the discharge tube. The siphon and crucible are thenlifted by means of a hoist, or the mold is lowered as previouslydescribed, and this relative lowering of the mold is continuedthroughout the remainder of the pouring operation to keep the level ofthe metal'in the tray and the mold above the level of the dischargeports 3 but below the level of the edges 6 of the tray. This relativeposition is essential, and is illustrated in Fig. 3. A

'I'he metal entering the tray through the ports spends the energyresulting from the relatively high velocity of its flow by setting themetal in the tray into a gentle rolling motion which is very efficaciousin separating any entrained dross from the metal and allowing it to riseto the surface by the action of gravity. The metal is further freed fromany solid impurities as it passes through the slots in the bottom of thetray. The area of the slots is several times greater than the area ofthe ports, and consequently the velocity of the metal entering the molditself is very low and the metal enters substantially withoutturbulence. When the casting operation is completed the siphon isremoved and the dross remains in the tray from which it may be easilyremoved.

It will be readily understood that my invention may take many formswithout departing from the principles set forth hereinabove and definedin the following claims.

I claim:

1. In a molten metal transfer device, a vertical tubular dischargemember with a discharge port opening laterally adjacent its end, saidend being closed by a tray supported therefrom and said tray having aperforate bottom plate and upturned edges extending above said dischargeport.

2. In a molten metal transfer device, a vertical tubular molten metaltransfer member with symmetrical lateral ports adjacent its dischargeend, said end being closed by a tray supported centrally therefrom andsaid tray having slots in the bottom thereof and edges extending abovesaid discharge ports. l

3. In a molten metal transfer device, a vertical tubular molten metaltransfer member with opposite discharge ports adjacent its dischargeend, said end being closed by and supporting centrally therefrom arectangular tray with transverse slots in the bottom plate thereof andedges extending above said discharge ports, said tray being sopositioned that said ports discharge into the tray along itslongitudinal axis and above its said bottom plate.

4. In a molten metal transfer system, a receiver for molten metal, and atubular discharge member extending downwardly into said receiver andhaving opposite lateral discharge ports adjacent its lower end, saidlower end being closed by a rectangular tray suspended centrallytherefrom and so positioned that the ports dischargealong itslongitudinal axis, said tray having a perforate bottom plate andupturned'edges extending above said discharge ports, and being sopositioned in relation to said receiver that the molten metal leveltherein is above said discharge ports and below the top of said upturnededges.

JOSEPH A. NOCK, JR.

